Answer: be deseasonalized by using a 4-quarter moving average

## Explanation For a time series with **quarterly seasonality** (i.e., a seasonal pattern that repeats every 4 quarters), the appropriate method to remove the seasonal component is to use a **4-quarter moving average**. ### Why 4-quarter moving average? - **Quarterly seasonality** means the pattern repeats every 4 periods (quarters) - A moving average with the same length as the seasonal period (4 quarters) will smooth out the seasonal fluctuations - The 4-quarter moving average effectively averages out the seasonal effects, leaving the trend and irregular components ### Why other options are incorrect: - **Option B (2-quarter)**: Too short - would not capture the full seasonal cycle - **Option C (3-quarter)**: Wrong length - doesn't match the quarterly seasonal pattern - **Option D**: Incorrect - moving averages are commonly used for deseasonalization This is a fundamental concept in time series analysis where moving averages are used to remove seasonal patterns when the moving average length equals the seasonal period.

Author: Tanishq Prabhu